Hybrid bipolar plate assembly and devices incorporating same

ABSTRACT

A hybrid bipolar plate assembly comprises a metallic anode plate, a polymeric composite cathode plate, and a metal layer positioned between the metallic anode plate and the composite cathode plate. The metallic anode and composite cathode plates can further comprise an adhesive sealant applied around the outer perimeter to prevent leaking of coolant. The assembly can be incorporated into a device comprising a fuel cell. Further, the device can define structure defining a vehicle powered by the fuel cell.

BACKGROUND OF THE INVENTION

Fuel cell systems with bipolar plates are known.

SUMMARY OF THE INVENTION

Fuel cells such as, for example, proton exchange membrane (PEM) fuelcells, produce electrical energy through hydrogen oxidation and oxygenreduction. The byproduct of these catalytic reactions is water. Atypical cell comprises a polymer membrane (e.g., proton exchangemembrane) that is positioned interjacent a pair of gas diffusion mediaand catalyst layers. A cathode plate and an anode plate are positionedat the outermost sides adjacent the gas diffusion media layers, and thepreceding components are tightly compressed to form the cell unit.

The voltage provided by a single cell unit is typically too small foruseful application. Accordingly, a plurality of cells are typicallyarranged and connected consecutively in a “stack” to increase theelectrical output of the electrochemical conversion assembly or fuelcell. In this arrangement, two adjacent cell units can share a commonpolar plate, which serves as the anode and the cathode for the twoadjacent cell units it connects in series. Such a polar plate iscommonly referred to as a “bipolar plate”.

Bipolar plates for fuel cells have to be electrochemically stable,electrically conductive, and inexpensive in order to comply with currentmanufacturing specifications. Both metallic and polymeric (composite)bipolar plates fulfill these criteria. However, composite plates arepermeable to hydrogen, which can lead to significant losses inperformance and efficiency. Such hydrogen permeation through compositeplates can result in the presence of hydrogen in the coolant loops,which requires venting thereof. This is not practical, as the venting ofthe coolant loops would lead to the evaporation of the coolant.

Unlike composite bipolar plates, metallic plates are essentiallyimpermeable to molecular hydrogen. However, metallic plates in contrastare relatively more expensive than composite plates, and are typicallyassociated with low performance cells. By “low performance cells”, wemean a cell within a fuel cell stack that exhibits a higher resistancethan the remaining cells, such as, for example, between about 200 andabout 250 mOhm-cm². Although not intending to be limited to anyparticular theory, it is contemplated that the poor performance ofmetallic bipolar plates is related to water management and, moreparticularly, to water management at the cathode side of the fuel cell,where water is produced. Accordingly, there is a recognized need forimprovements in bipolar plate design for fuel cell stacks.

The present invention fulfills this need by providing a hybrid bipolarplate assembly for use in a fuel cell, which assembly combines theuseful properties of both metal and composite materials. Although thepresent invention is not limited to specific advantages orfunctionality, it is noted that the hybrid bipolar plate assemblyprevents plate to plate hydrogen permeation, and eliminates hydrogenpermeation through the plate to the coolant. The hybrid bipolar plateassembly enhances the performance, efficiency and durability of the fuelcell stack. Moreover, the present invention eliminates hydrogen leakingto the environment, and allows for cost reduction by employing lessstainless steel than a typical metallic bipolar plate.

In accordance with one embodiment of the present invention, a hybridbipolar plate assembly is provided comprising a metallic anode plate, apolymeric composite cathode plate, and a first layer comprising at leastone of gold, silver and alloys of each positioned between the metallicanode plate and the composite cathode plate.

In accordance with another embodiment of the present invention, a deviceis provided comprising a polymer membrane, first and second catalystlayers, first and second gas diffusion media layers, and at least onehybrid bipolar plate assembly. The polymer membrane defines opposingcathode and anode faces on opposite sides of the membrane. The first andsecond catalyst layers define opposing inside and outside faces onopposite sides of the catalyst. The inside face of the first catalystlayer engages the cathode face of the polymer membrane, and the insideface of the second catalyst layer engages the anode face of the polymermembrane. The first and second gas diffusion media layers defineopposing inside and outside faces on opposite sides of the gas diffusionmedia. The inside face of the first gas diffusion media layer engagesthe outside face of the first catalyst layer, and the inside face of thesecond gas diffusion media layer engages the outside face of the secondcatalyst layer. The hybrid bipolar plate assembly engages at least oneof the first and second gas diffusion media layers. Also, the hybridbipolar plate assembly comprises a metallic anode plate, a compositecathode plate, and a layer comprising at least one of gold, silver andalloys of each. The metallic anode plate defines opposing first andsecond major faces on opposite sides of the metallic anode plate, andthe composite cathode plate comprises a polymeric material. The layerthat can comprise at least one of gold, silver and alloys of eachengages at least one of the first and second major faces of the metallicanode plate. The device can comprise a fuel cell, and the device canfurther comprise structure defining a vehicle powered by the fuel cell.

In accordance yet with another embodiment of the present invention, ahybrid bipolar plate assembly is provided comprising a metallic anodeplate, a composite cathode plate, a layer comprising at least one ofgold, silver and alloys of each positioned between the metallic anodeplate and the composite cathode plate, and an adhesive. The metallicanode plate comprises a corrosion-resistant iron-chromium alloy, and thecomposite cathode plate comprises a polymeric material and between about10 and about 90% by weight graphite powder. The polymeric material canbe selected from thermosetting resin, thermoplastic resin, orcombinations thereof. The thermosetting resin can comprise at least oneof epoxies, malamines, phenolics, ureas, vinyl esters, liquidcrystalline polymers, and combinations thereof. Also, the thermoplasticresin can comprise at least one of styrenes, acrylics, cellulosics,polyethylenes, polypropylene, liquid crystalline polymers, vinyls,nylons, fluorocarbons, polyphenylene sulfides, and combinations thereof.In addition, the web thickness of the metallic anode plate is less thanthe web thickness of the composite cathode plate. The adhesive isconfigured to seal the metallic anode plate and the composite cathodeplate around the outer perimeter of the hybrid bipolar plate assembly,such that coolant is prevented from leaking out from between themetallic anode plate and the composite cathode plate. Optionally, thehybrid bipolar plate assembly can comprise a gasket configured toprevent coolant from leaking out from between the metallic anode plateand the composite cathode plate.

In accordance with still yet another embodiment of the presentinvention, a hybrid bipolar plate assembly is provided comprising ananode plate comprising a first layer and a second layer, the first layercomprising a first metal, the second layer comprising a second metal,and wherein the second layer is chemically stable in the presence ofcoolant. The assembly can further comprise a composite cathode plate,and the anode plate can be substantially devoid of any oxide on thefirst layer. The anode plate can comprise a coolant face and the firstmetal can comprise iron and Cr, wherein any oxides of Cr have beensubstantially removed from the coolant face. The second metal cancomprise at least one of gold, silver and alloys of each.

These and other features and advantages of the invention will be morefully understood from the following detailed description of theinvention taken together with the accompanying claims. It is noted thatthe scope of the claims is defined by the recitations therein and not bythe specific discussion of features and advantages set forth in thepresent description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the embodiments of the presentinvention can be best understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is an isometric, exploded view of a hybrid bipolar plateassembly, anode side up, in accordance with the principals of thepresent invention;

FIG. 2 is a cross-sectional, partial view of a hybrid bipolar plateassembly arranged in a stack in accordance with the principals of thepresent invention;

FIG. 3 is an enlarged sectional view of the hybrid bipolar plateassembly illustrated in FIG. 2; and

FIG. 4 is a schematic illustration of a vehicle incorporating anelectrochemical conversion assembly in accordance with the principals ofthe present invention.

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help improve understandingof embodiment(s) of the present invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

In accordance with one embodiment of the present invention, a hybridbipolar plate assembly 1 is provided, which assembly 1 can be used in anelectrochemical conversion assembly (e.g., fuel cell). The assembly 1comprises a metallic anode plate 2, a composite cathode plate 4, and afirst layer 3 positioned between the metallic anode plate 2 and thecomposite cathode plate 4, which hybrid bipolar plate assembly 1 isillustrated in FIGS. 1, 2 and 3. The first layer 3 can comprise at leastone of gold, silver and alloys of each. By employing the usefulproperties of both metals and composites, the hybrid bipolar plateassembly 1 addresses many of the drawbacks typically encountered withconventional bipolar plates that are entirely comprised of eithermetallic or composite materials. More particularly, the hybrid bipolarplate assembly 1 of the present invention takes advantage of the greatermechanical strength and lower thickness provided by metallic plates, andthe improved water management provided by composite plates, as comparedto metallic plates. Moreover, unlike composite bipolar plates, metallicplates are essentially impermeable to molecular hydrogen and, therefore,do not allow hydrogen to enter the coolant loops, which can lead tosignificant losses in fuel cell performance and efficiency.

The metallic anode plate 2 can comprise a corrosion-resistantiron-chromium alloy material (e.g., stainless steel), and the compositecathode plate 4 can comprise a polymeric material such as athermosetting resin, a thermoplastic resin, or combinations thereof. Thethermosetting resin can be selected from epoxies, malamines, phenolics,ureas, vinyl esters, polyesters, and combinations thereof, and thethermoplastic resin can be selected from styrenes, acrylics,cellulosics, polyethylenes, polypropylenes, liquid crystalline polymers(polyesters), vinyls, nylons, fluorocarbons, polyphenylene sulfides, andcombinations thereof. Typically, the composite cathode plate 4 comprisesbetween about 10 and about 90% by weight graphite powder, which graphitepowder can be selected from synthetic graphite, natural graphite, orcombinations thereof. The graphite enhances the electrical conductivityof the composite cathode plate 4.

FIG. 1 is an exploded view of the hybrid bipolar plate assembly 1 inaccordance with one embodiment of the present invention. The assembly 1provides a reactant gas flow field characterized by a plurality ofserpentine gas flow channels 20 through which the electrochemicalconversion assembly's reactant gases (i.e., H₂ and O₂) flow in atortuous path from near one edge 22 of the bipolar plate assembly 1 tonear the opposite edge 24 thereof. The reactant gas is supplied tochannels 20 from a header or supply manifold groove 21 that liesadjacent the edge 22 of the plate assembly 1 at one end of the flowfield, and exits the channels 20 via an exhaust manifold groove 23 thatlies adjacent the opposite edge 24 of the assembly 1 at the other end ofthe flow field. Alternatively, the supply and exhaust manifolds 21, 23can lie adjacent the same edge (i.e., 22 or 24) of the plate assembly 1.

FIG. 2 is a cross-sectional view of a pair of hybrid bipolar plateassemblies 1 that are arranged in a stack in accordance with the presentinvention. Typically, as illustrated in FIG. 2, a MEA 5 positionedinterjacent a pair of diffusion media layers 7 are oriented between thepair of hybrid bipolar plate assemblies 1, which plates are compressedto form one complete cell. It is contemplated that the MEA 5 anddiffusion media layers 7 may take a variety of conventional or yet to bedeveloped forms without departing from the scope of the presentinvention. Although the particular form of the MEA 5 is beyond the scopeof the present invention, the MEA 5 can include respective catalyticelectrode layers and an ion exchange membrane. Both the metallic anodeplate 2 and the composite cathode plate 4 include a plurality ofchannels which together form passages or “coolant cavities” 6 throughwhich liquid coolant passes during the operation of the electrochemicalconversion assembly. Also, the metallic anode and composite cathodeplates 2, 4 each comprise one or more anode or cathode channels 8, 10,respectively. The anode channel 8 is configured for the passage of H₂gas and the cathode channel 10 is configured for the passage of O₂ gasor air.

Although not wishing to limit the present invention to any particularmethod of manufacture, the anode channel 8 is typically stamped into themetallic anode plate 2, and the cathode channel 10 is typically moldedinto the composite cathode plate 4. The depth of these channels 8, 10 issubstantially similar. However, the metallic anode plate 2 and compositecathode plate 4 each define a web thickness that can differ given themechanical properties of the metallic anode and composite cathode plates2, 4. By “web thickness” we mean the plate thickness between the bottomof the gas channel (anode 8 or cathode 10) and the top of the coolantchannel that forms the coolant cavity 6 (see FIG. 2). The compositematerial that makes up the cathode plate 4 is typically comparablyweaker than the metallic material of the anode plate 2. This is at leastpartially because of the high loading of graphite that is incorporatedinto the composite material to increase the electrical conductivity ofthe cathode plate 4. As such, the metallic anode plate 2 can have athinner web thickness than the composite cathode plate 4. As shown withmore particularity in FIG. 3, the web thickness a of the metallic anodeplate 2 is less than the web thickness b of the composite cathode plate4. Typically, the web thickness a of the metallic anode plate 2 isbetween about 0.1 and about 0.15 mm, and the web thickness b of thecomposite cathode plate 4 is between about 0.3 and about 0.8 mm.

As noted herein, the metallic anode plate 2 is configured to beessentially impermeable to molecular hydrogen. As such, the hydrogenousfuel source is maintained within the anode channel 8 and does notpermeate into the coolant cavity 6 or escape to the atmosphere. Thisimproves fuel cell performance and efficiency, as hydrogen need not bevented from the coolant cavity 6, which can contribute to evaporation ofcoolant and inefficient use of hydrogen fuel for the generation ofelectrical power. In addition, the use of composite material in themanufacture of the cathode plate 4 provides a hybrid bipolar plateassembly 1 with significantly less material cost than conventionalentirely metallic bipolar plate assemblies, while still benefiting fromthe properties of metallic material.

As noted herein, water is produced as a byproduct of the catalyticreaction that occurs within the fuel cell assembly, which water exitsthe fuel cell through the gas distribution channels. This creates a masstransport problem for the reactive gases (i.e., H₂ and O₂) that cannotphysically reach the catalyst layer to react because the liquid water“plugs” the gas channels. As a result, these cells that are blocked bywater in the gas distribution channels exhibit a much lower voltage thanthe rest of the cells in a fuel cell stack. The performance of theseblocked cells can degrade with time until the entire electrochemicalconversion assembly fails. Because the individual cells are connected inseries by bipolar plates, if one cell fails due to water in the gasdistribution channels, the entire fuel cell stack will eventually ceaseto operate. The frequency of this problem is much higher with metallicbipolar plates compared with composites because of the design andcoating material constraints associated with corrosion-resistant metalalloys (e.g., stainless steel materials). Water management is consideredas one of the most difficult problems to solve in fuel cells.

In accordance with the present invention, the hybrid bipolar plateassembly 1 enables effective water management at the cathode side of theelectrochemical conversion assembly, where water is produced. This isaccomplished by employing a composite cathode plate 4, which compositematerial provides greater design freedom to tailor the geometry of thegas diffusion channels and the resin material properties (hydrophilicand hydrophobic) to effectively and efficiently purge the water out ofthe gas diffusion channels versus coated stainless steel plates, whichmaterial properties do not afford such flexibility. Accordingly, theproperties of the composite plate 4 can be easily changed bysubstituting different binders used in making the composite. Incontrast, the geometry of stamped metallic bipolar plates is limitedbecause these materials can tear at large strains during stamping,dependent upon the channel geometry.

In accordance with the present invention, the hybrid bipolar plateassembly 1 can further comprise a metal or metal alloy layer 3 that isapplied on one or both sides of the metallic anode plate 2. The metal ormetal alloy layer 3 should be chemically stable in the presence of acoolant if positioned to be in contact therewith. Suitable materials forthe metal or metal alloy include but are not limited to gold, goldalloys, silver and silver alloys. In the embodiment illustrated in FIGS.2 and 3, the metal or metal alloy layer 3 is applied to both sides ofthe metallic anode plate 2. The metal or metal alloy layer 3 istypically pure gold, which can be applied to the metallic anode plate 2using a physical vapor deposition process such as, for example, electronbeam deposition or sputtering, or an electroplating process. The metalor metal alloy layer 3 is typically between about 2 and about 50 nmthick.

Corrosion-resistant iron-chromium alloys such as stainless steel cannotbe used in an uncoated state in an electrochemical conversion assemblybecause of the passive oxide film on its surface, which creates a highcontact resistance with the gas diffusion media. The passive layer,which is typically mainly Cr₂O₃, protects the metallic alloy from thecorrosive environment within the cell, but is electrically resistant.Therefore, in accordance with the present invention, the passive layeris reduced or removed via hydrofluoric acid etching or cathodiccleaning, and the surface of the metallic alloy plate 2 is typicallycoated with gold in order to minimize the contact resistance on thesurface.

Further, in accordance with the present invention, gold is typicallyemployed on the back or coolant side of the metallic anode plate 2 inorder to minimize the contact resistance between it and the compositecathode plate 4. This minimizes voltage losses between the cells, whichare arranged in series in a stack. A lower bond line resistance isdesirable to avoid voltage losses through the bond lines. The bond lineresistance between the gold-coated metallic anode plate 2 and thecomposite cathode plate 4 is typically between about 1.8 and about 2mOhm-cm². Accordingly, the present invention allows for the eliminationof conventional bonding processes that are typically cost prohibitivefor both metallic and composite plates.

An adhesive can be used around the perimeter of the metallic anode 2 andcomposite cathode plates 4 in order to seal the stack and preventcoolant from leaking out from the hybrid bipolar plate assembly 1. Theadhesive can be either conductive or non-conductive, and can be selectedfrom a thermosetting resin, a thermoplastic resin, or combinationsthereof, such as, for example, epoxies, phenolics, acrylics, urethanes,polyesters, etc. The adhesive can be applied using any one of thefollowing processes: dispensing, screen and silk printing, spray androll coating, etc. Alternatively, a gasket configured to prevent coolantfrom leaking out from the hybrid bipolar plate assembly 1 can beemployed with or without the adhesive sealant. In accordance with thepresent invention, the direct contact between the composite cathodeplate 4 and the typically gold coated metallic anode plate 2, with orwithout the use of the conductive or non-conductive adhesive around theoutside perimeter of the plates 2, 4, maintains the integrity of thefuel cell stack and is cost effective.

Referring now to FIG. 4, a fuel cell system incorporating at least onehybrid bipolar plate assembly according to the present invention may beconfigured to operate as a source of power for a vehicle 100.Specifically, fuel from a fuel storage unit 120 may be directed to afuel cell assembly 110 configured to convert fuel, e.g., H₂, intoelectricity. The electricity generated is used as a motive power supplyfor the vehicle 100 where the electricity is converted to torque andvehicle translational motion. Although the vehicle 100 shown in FIG. 4is a passenger automobile, it is contemplated that the vehicle 100 canbe any vehicle now known or later developed that is capable of beingpowered or propelled by a fuel cell system, such as, for example,automobiles (i.e., car, light- or heavy-duty truck, or tractor trailer),farm equipment, aircraft, watercraft, railroad engines, etc.

It is noted that terms like “preferably”, “commonly” and “typically” arenot utilized herein to limit the scope of the claimed invention or toimply that certain features are critical, essential, or even importantto the structure or function of the claimed invention. Rather, theseterms are merely intended to highlight alternative or additionalfeatures that may or may not be utilized in a particular embodiment ofthe present invention.

For the purposes of describing and defining the present invention it isnoted that the term “device” is utilized herein to represent acombination of components and individual components, regardless ofwhether the components are combined with other components. For example,a “device” according to the present invention may comprise a hybridbipolar plate assembly, a fuel cell incorporating a hybrid bipolar plateassembly according to the present invention, a vehicle incorporating afuel cell according to the present invention, etc.

For the purposes of describing and defining the present invention it isnoted that the term “substantially” is utilized herein to represent theinherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement, or other representation.The term “substantially” is also utilized herein to represent the degreeby which a quantitative representation may vary from a stated referencewithout resulting in a change in the basic function of the subjectmatter at issue.

Having described the invention in detail and by reference to specificembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of theinvention defined in the appended claims. More specifically, althoughsome aspects of the present invention are identified herein as preferredor particularly advantageous, it is contemplated that the presentinvention is not necessarily limited to these preferred aspects of theinvention.

What is claimed is:
 1. A stacked device comprising: a first polymermembrane defining opposing cathode and anode faces on opposite sides ofsaid first polymer membrane; a first layer of catalyst defining opposinginside and outside faces on opposite sides of said first layer ofcatalyst, said inside face engaging said cathode face of said firstpolymer membrane; a second layer of catalyst defining opposing insideand outside faces on opposite sides of said second layer of catalyst,said inside face engaging said anode face of said first polymermembrane; a first layer of gas diffusion media defining opposing insideand outside faces on opposite sides of said first layer of gas diffusionmedia, said inside face engaging said outside face of said first layerof catalyst; a second layer of gas diffusion media defining opposinginside and outside faces on opposite sides of said second layer of gasdiffusion media, said inside face engaging said outside face of saidsecond layer of catalyst; a first hybrid bipolar plate assemblycomprising a first metallic anode plate defining opposing inside andoutside major faces on opposite sides of said first metallic anodeplate, the inside major face of the first metallic anode directlyengaging the outside face of the second layer of gas diffusion media,wherein at least one of the inside and outside major faces of the firstmetallic anode plate comprises a first corrosion-preventive layercomprising at least one of gold, silver, and alloys of each, and a firstcomposite cathode plate engaging the outside major face of the firstmetallic anode plate, wherein said first composite cathode platecomprises a first polymeric material; and a second hybrid bipolar plateassembly comprising a second composite cathode plate defining opposinginside and outside major faces on opposite sides of the second compositecathode plate, the inside major face of the second composite cathodeplate engaging the outside face of the first layer of gas diffusionmedia, wherein said second composite cathode plate comprises a secondpolymeric material, and a second metallic anode plate defining opposinginside and outside major faces on opposite sides of said second metallicanode plate, the inside major face of the second metallic anode plateengaging the outside major face of the second composite cathode plate,wherein at least one of the inside and outside major faces of the secondmetallic anode plate comprises a second corrosion-preventive layercomprising at least one of gold, silver, and alloys of each.
 2. Thestacked device of claim 1, wherein at least one of said first and secondmetallic anode plates comprise a corrosion-resistant iron-chromium alloymaterial.
 3. The stacked device of claim 1, wherein at least one of saidfirst and second polymeric materials comprise a thermosetting resin, athermoplastic resin, or combinations thereof.
 4. The stacked device ofclaim 3, wherein said thermosetting resin comprises at least one ofepoxies, malamines, phenolics, ureas, vinyl esters, polyesters, andcombinations thereof.
 5. The stacked device of claim 3, wherein saidthermoplastic resin comprises at least one of styrenes, acrylics,cellulosics, polyethylenes, polypropylenes, liquid crystalline polymers,vinyls, nylons, fluorocarbons, polyphenylene sulfides, and combinationsthereof.
 6. The stacked device of claim 1, wherein at least one of saidfirst and second composite cathode plates comprise between 10% and 90%by weight graphite powder.
 7. The stacked device of claim 6, whereinsaid graphite powder comprises at least one of synthetic graphite,natural graphite, and combinations thereof.
 8. The stacked device ofclaim 1, wherein the inside major face of the first metallic anode plateand the outside face of the second layer of gas diffusion media defineone or more anode channels, said anode channels configured for thepassage of H₂ gas.
 9. The stacked device of claim 1, wherein the insidemajor face of the second composite cathode plate and the outside face ofthe first layer of gas diffusion media define one or more cathodechannels, said cathode channels configured for the passage of O₂ gas orair.
 10. The stacked device of claim 1, wherein the first metallic anodeplate and the first composite cathode plate, or the second metallicanode plate and the second composite cathode plate, or both, define oneor more coolant channels for passage of a liquid.
 11. The stacked deviceof claim 1, wherein said first and second metallic anode plates and saidfirst and second composite cathode plates each define a web thickness,said web thickness of said first metallic anode plate is less than saidweb thickness of said first composite cathode plate, and said webthickness of said second metallic anode plate is less than said webthickness of said second composite cathode plate.
 12. The stacked deviceof claim 11, wherein said web thickness of at least one of said firstand second metallic anode plates is between 0.1 mm and 0.15 mm, andwherein said web thickness of at least one of said first and secondcomposite cathode plates is between 0.3 mm and 0.8 mm.
 13. The stackeddevice of claim 1, wherein at least one of said first and secondcorrosion-preventive layers is between 2 nm and 50 nm thick.
 14. Thestacked device of claim 1 further comprising an adhesive configured toseal at least one of (a) said first metallic anode plate and said firstcomposite cathode plate, or (b) said second metallic anode plate andsaid second composite cathode plate around an outer perimeter of atleast one of said first and second hybrid bipolar plate assemblies. 15.The stacked device of claim 14, wherein said adhesive is configured toprevent coolant from leaking out from between said metallic anode platesand said composite cathode plates.
 16. The stacked device of claim 14,wherein said adhesive is non-conductive.
 17. The stacked device of claim14, wherein said adhesive is conductive.
 18. The stacked device of claim14, wherein said adhesive comprises at least one of a thermosettingresin, a thermoplastic resin, and combinations thereof.
 19. The stackeddevice of claim 1 further comprising a gasket configured to preventcoolant from leaking out from between said metallic anode plates andsaid composite cathode plates.
 20. The stacked device of claim 1,wherein said stacked device comprises a fuel cell.
 21. The stackeddevice of claim 20 further comprising structure defining a vehiclepowered by said fuel cell.
 22. The stacked device of claim 1, furthercomprising: a second polymer membrane defining opposing cathode andanode faces on opposite sides of the second polymer membrane; a thirdlayer of catalyst defining opposing inside and outside faces on oppositesides of the third layer of catalyst, said inside face engaging thecathode face of the second polymer membrane; a fourth layer of catalystdefining opposing inside and outside faces on opposite sides of thefourth layer of catalyst, said inside face engaging the anode face ofthe second polymer membrane; a third layer of gas diffusion mediadefining opposing inside and outside faces on opposite sides of thethird layer of gas diffusion media, said inside face engaging theoutside face of the third layer of catalyst; and a fourth layer of gasdiffusion media defining opposing inside and outside faces on oppositesides of the fourth layer of gas diffusion media, said inside faceengaging the outside face of the fourth layer of catalyst, said outsideface engaging the outside major face of the second metallic anode plate.